How would you handle when a new season starts? Depending on the sport, this may be at different dates! Some new seasons start in spring (april/may), summer (july/august), some start in fall (september/october) and some start even in winter, like alpine ski (november/december). You would have to add some sort of qualifier that states the month in which a season starts, for example {season:4:year4-year2} to get the season starting in april and a specification how a season should be typeset (resulting in 2026-27 when called in may and 2025-26 when called in march).